JPH05277660A - Method for continuously casting clad steel sheet by twin rolls - Google Patents

Abstract

PURPOSE:To provide a continuous casting method preventing the mixture of molten metals at upper and lower layers in a molten metal pouring basin part, in the casting method for continuously producing a clad steel sheet by twin rolls. CONSTITUTION:By arranging magnetic poles 6a at the outside in both end surfaces of side weirs 2 arranged at both surfaces of twin rolls 1, a boundary layer is formed by a static magnetic field zone 7 in the molten metal pouring basin part 3. Then, the molten metal for forming the outer layer solidified shell 8a at the upper layer of the boundary layer and the molten metal for forming the inner layer solidified shell 8b at the lower layer are poured and the solidified shells at the inner and the outer layers are integratively composed at the roll kiss 10 point or the front or the rear parts thereof to produce the clad steel sheet. By this method, the mixture of the molten metals at the upper and the lower layers in the molten metal pouring basin parts can be prevented and therefore, this method is applied to the production of the clad steel sheet using the material having different densities too and the clad steel sheet having extremely clear boundary of the inner and the outer layers is obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a casting method for continuously producing a clad steel plate by compounding different kinds of molten metals by twin roll type continuous casting for producing a thin plate slab.

[0002]

2. Description of the Related Art Conventionally, as a technique for producing a clad steel sheet, a method based on a rolling method or an explosion deposition method is known. These techniques are methods in which individually manufactured sheet materials are brought into close contact with each other by rolling or explosive force.

However, the above-mentioned method needs to be individually rolled to manufacture the plate materials to be composited, and it takes a lot of time and cost to combine the composite materials, so that it is not applied so much at present.

As a method for solving the above problems, a continuous casting method of a composite metal material using a rectangular cooling mold has been used conventionally. However, this method has a slab thickness of 100
This is a technology for ultra-thick slabs with a thickness of mm or more. To make it into a practical clad steel plate, it is necessary to go through steps such as hot rolling and cold rolling. Still, the problem of high cost still remains.

As an alternative technique, a technique for directly producing a multi-layer metal material having a predetermined thickness, that is, a clad steel sheet by twin roll type continuous casting has been considered recently.

FIG. 7 is a drawing showing a comparative example of a continuous casting method of a clad steel plate by twin rolls, and this technique uses two rolls 41 and side weirs provided on both side surfaces of the rolls.
Thus, two pouring nozzles 44a and 44b having different lengths are immersed in the formed pool 43, and different kinds of molten metals are respectively injected into the pouring nozzles to form two upper and lower molten metal layers in the pool 43. 43a and 43b are formed.

Then, the outer layer solidified shell 45a is formed by the upper layer molten metal in contact with the roll 41, the inner layer solidified shell 45b is subsequently formed by the lower layer molten metal, and the inner and outer layer solidified shells 45a, 45b are formed by roll kiss points 46.
Is a continuous casting method for a clad steel plate by twin rolls, in which the clad steel plate 47 is manufactured by integrally compounding.

[0008]

By the way, this technique is
There is a risk that different kinds of molten metals will coexist in the molten metal pool 43 and two kinds of molten metals will be mixed. Therefore, in order to avoid this mixing, the molten metal forming the upper layer molten metal layer 43a, that is, the outer layer solidified shell 45a must have a lower density than the lower layer molten metal forming the inner layer solidified shell 45b.

For this reason, this method cannot be applied to the production of a clad steel sheet using a material having a higher density in the outer layer than in the inner layer, for example, a clad steel sheet in which the inner layer is a normal mild steel material and the outer layer is a stainless steel material. ..

The present invention has been made in view of the above problems,
Provided is a continuous casting method for a clad steel plate which prevents the upper and lower layers of molten metal from being mixed in a molten metal pool in twin roll continuous casting.

[0011]

According to a first aspect of the present invention, two pouring nozzles having different lengths are dipped in a basin formed by two rolls and side dams provided on both side surfaces of the rolls. In the continuous casting method of manufacturing a clad steel plate by injecting different kinds of molten metals by the injection nozzles to form upper and lower two layers of molten metal in the pool, magnetic poles are arranged on both sides of the roll. A boundary layer is formed in the molten metal pool by a static magnetic field band, and molten metal for forming an outer layer solidified shell on the upper layer of the boundary layer and molten metal for forming an inner layer solidified shell on the lower layer are respectively injected to solidify the inner and outer layers. A continuous casting method for a clad steel plate by twin rolls, characterized in that a shell is integrally compounded at a roll kiss point to produce a clad steel plate.

In the second aspect of the present invention, two pouring nozzles having different lengths are dipped in a molten metal pool formed by two rolls and side dams provided on both side surfaces of the rolls, and the pouring nozzles are used. In a continuous casting method for producing a clad steel sheet by injecting different kinds of molten metals into each other and forming molten metal layers of upper and lower two layers in a pool, a long injection nozzle for injecting the molten metal into the lower layer of the injection nozzles is used. In addition to providing horizontally extending separators, magnetic poles are arranged on both sides of the roll to form a static magnetic field band at a position overlapping with the separators, and the outer layer is solidified on the boundary layer between the separator and the static magnetic field band. A molten metal that forms a shell and a molten metal that forms an inner layer solidified shell are respectively injected into the lower layers, and the solidified shells of the inner and outer layers are integrally combined at a roll kiss point to produce a clad steel sheet. Which is a continuous casting method of the clad steel sheet by twin roll characterized.

[0013]

[Function] By applying a static magnetic field band in the molten metal in the transverse direction, the static magnetic field band forms a boundary layer of the molten metal,
It is well known that the molten metal above and below the static magnetic field zone is subjected to a flow braking force (electromagnetic brake) to suppress mixing.

The present invention relates to a method for continuously casting thin plate slabs by twin rolls known as the Bessemer method.
For example, an electromagnet is arranged on each roll and side weirs provided on both side surfaces of the roll, and the electromagnet forms a boundary layer by a static magnetic field band that horizontally traverses the inside of the basin.
The book pouring nozzle is immersed above and below the boundary layer, and different kinds of molten metals are injected from the respective pouring nozzles to form two upper and lower molten metal layers in the basin while preventing mixing.

Further, in a molten metal pool formed by two rolls and side weirs provided on both sides of the rolls, a separator plate horizontally extended to a long injection nozzle for injecting molten metal into a lower layer of the immersion nozzles to be immersed. In addition, a static magnetic field band is formed horizontally by disposing, for example, an electromagnet at a position overlapping the separator, and different types of molten metal are injected from above and below the boundary layer formed by the separator and the static magnetic field band from the respective injection nozzles. Then, the molten metal layers of the upper and lower two layers are formed in the pool part while preventing mixing.

The upper molten metal layer of the boundary layer is then cooled by a roll to form an outer layer solidified shell, and the lower molten metal layer is cooled by an outer layer solidified shell to form an inner layer solidified shell inside the outer layer. The layer-solidified shell is integrally compounded at a roll kiss point to form a multi-layer cast piece, and a clad steel plate is manufactured.

In this case, if the separator is made too large, it may break the outer layer solidified shell formed on the surface of the roll and the molten metal may break out to the outside of the apparatus. Therefore, it is necessary to determine the size in consideration of the thickness of the outer layer solidified shell to be formed.

As described above, even if the molten metal having different densities is injected into the upper and lower layers by the static magnetic field band between the upper and lower two molten metal layers, and the boundary layer formed by the separator and the static magnetic field band, both molten metal Since the molten metal does not mix in the produced clad steel sheet which is not mixed with each other, a slab having an extremely clear boundary between the outer layer and the inner layer is formed, and an excellent clad steel sheet is obtained.

[0019]

1 to 3 are drawings showing a first embodiment of a twin roll type continuous casting apparatus for producing a clad steel sheet suitable for carrying out the present invention, and FIG. 1 is a side view and FIG. Is a plan view and FIG. 3 is a front view.

In this continuous casting apparatus, two pouring nozzles 4a and 4b having different lengths are immersed in a pool 3 formed by two rolls 1 and side dams 2 provided on both sides of the rolls. The molten metal of different types is injected from both nozzles, and the molten metal layer 3a is composed of two upper and lower layers,
3b is formed.

Further, in this apparatus, electromagnets 6 are arranged on the side surfaces of the side dams 2 to form a boundary layer by a static magnetic field band 7 which horizontally traverses the inside of the basin 3 and forms a boundary layer between the two injection nozzles. The molten metal injected from the short injection nozzle 4a immersed in the upper layer forms the molten metal layer 3a, and the molten metal injected from the long injection nozzle 4b immersed in the lower layer forms the molten metal layer 3b.

The electromagnet 6 is formed by arranging magnetic poles 5a of different polarities, each having a coil 6b wound around the outer surface of the side dam 2, and coupled by a high permeability yoke 6c surrounding the roll 1. It

The molten metal of the molten metal layers 3a and 3b formed in the upper and lower layers of the static magnetic field zone 7 is subjected to a flow damping force by the boundary layer formed by the static magnetic field zone 7, and the molten metal pool 3 is formed.
There is no mixing in the upper and lower parts.

The molten metal forming the upper molten metal layer 3a is cooled by the roll 1 and starts to solidify at the solidification starting point 8a in contact with the molten metal surface, and the outer layer solidified shell 9a.
Is induced downward while forming the.

The molten metal forming the lower molten metal layer 3b is cooled by the outer layer solidification shell 9a, and the solidification starting point 8 is reached at the level of the boundary layer formed by the static magnetic field zone 7.
b as the inner layer solidified shell 9 inside the outer layer solidified shell 9a
b is formed.

Then, the solidified shells 9a and 9b for the inner and outer layers are formed.
Are composited together at the roll kiss point 10 to form a multilayer cast slab 1
1 and a clad steel plate is manufactured.

4 to 6 are drawings showing a second embodiment, FIG. 4 is a side view, FIG. 5 is a plan view, and FIG. 6 is a front view.

In the continuous casting apparatus, two pouring nozzles 24 having different lengths are provided in a molten metal pool 23 formed by two rolls 21 and side dams 22 provided on both side surfaces of the rolls.
a and 24b are immersed, and different types of molten metals are injected from both nozzles to form two upper and lower molten metal layers 23a and 23b in the basin 23.

Further, the present apparatus has two injection nozzles 24.
Long injection nozzle 2 to be immersed in the lower layer of a and 24b
On the 4b side, a separating plate 25 that horizontally spreads is provided at an isolated portion of both molten metals forming a boundary between the upper and lower two molten metal layers 23a and 23b, and an electromagnet 26 is further disposed on the side surface of the side dam 22 to isolate the molten metal layers 23a and 23b. A static magnetic field band 27 is formed at a position overlapping with the plate 25, and a molten metal injected from a short injection nozzle 24a immersed in an upper layer of a boundary layer formed by the separator 25 and the static magnetic field band 27 forms a molten metal layer 23a. Then, the molten metal injected from the long injection nozzle 24b immersed in the lower layer forms the molten metal layer 23b.

The electromagnet 26 is formed by arranging magnetic poles 25a of different polarities, each having a coil 26b wound around the outer surface of the side dam 22, and being connected by a high-permeability yoke 26c surrounding the roll 21. It

The molten metal in the molten metal layers 23a and 23b above and below the boundary layer formed by the separator 25 and the static magnetic field band 27 is subjected to the separating action of the separator 25 and the flow braking force of the static magnetic field band 27, so that the molten metal In the reservoir 23, they are not completely separated into upper and lower parts and mixed.

Here, the molten metal forming the molten metal layer 23a is cooled by the roll 21 and begins to solidify at the solidification start point 28a in contact with the molten metal surface, and the outer layer solidified shell 2
It is guided downward while forming 9a.

The molten metal forming the molten metal layer 23b is cooled by the outer layer solidification shell 29a, and the boundary layer level formed by the separator 25 and the static magnetic field zone 27 in the basin 23 is used as the solidification starting point 28b. Outer layer solidified shell 2
The inner layer solidified shell 29b is formed inside 9a.

Since the separator 25 is located in the middle of the outer layer solidified shell 29a formed in the two rolls 21, if it is made too large, the outer layer solidified shell 29a formed on the surface of the roll is broken. , It becomes a breakout where the molten metal flows out of the equipment. Therefore, it is necessary to determine the size in consideration of the thickness of the outer layer solidified shell 29a to be formed.

Then, the solidified shells 29a, 2 of the inner and outer layers are formed.
9b is integrally compounded at the roll kiss point 30 to form a multilayer cast slab 31, and a clad steel plate is manufactured.

In the first and second embodiments, the magnetic poles 6a and 26a are
Although the electromagnets 6 and 26 have been used as means for arranging the above to form the static magnetic field bands 7 and 27, permanent magnets may be used instead of the electromagnets to form the static magnetic field bands.

As described above, by forming the boundary layer of the static magnetic field band that horizontally traverses the inside of the basin or the boundary layer of the separator and the static magnetic field band, it is possible to prevent the molten metal in the upper and lower layers from being mixed. Therefore, the boundary between the outer layer and the inner layer becomes an extremely clear slab, and an excellent clad steel plate can be obtained.

Further, by providing the boundary layer of the static magnetic field band and the separator in this way, even if the molten metals having different densities are injected into the upper and lower layers, the molten metals do not mix with each other. It is possible to manufacture a clad steel sheet using a material having a higher density in the upper layer or outer layer.

[0039]

As described above, according to the present invention, the mixing of the molten metal in the upper and lower layers of the basin is prevented by providing the basin layer of the static magnetic field band or the separator and the static magnetic field band in the basin. Therefore, it can be applied to the production of a clad steel sheet using materials having different densities in the inner and outer layers, and a slab with a very clear boundary between the outer layer and the inner layer can be obtained to obtain a good quality clad steel sheet.

[Brief description of drawings]

FIG. 1 is a side view showing a first embodiment of a twin roll type continuous casting apparatus for producing a clad steel sheet suitable for carrying out the present invention.

FIG. 2 is a plan view of FIG.

FIG. 3 is a front view of FIG.

FIG. 4 is a side view showing a second embodiment of a twin roll type continuous casting apparatus for producing a clad steel sheet suitable for carrying out the present invention.

FIG. 5 is a plan view of FIG.

FIG. 6 is a front view of FIG.

FIG. 7 is a drawing showing a comparative example of a method for producing a clad steel plate by a twin roll type continuous casting device.

[Explanation of symbols]

 1, 21 Casting rolls 2, 22 Side weirs 3, 23 Hot water pool parts 3a, 23a Upper molten metal layers 3b, 23b Lower molten metal layers 4a, 24a Injection nozzles for upper layers 4b, 24b Injection nozzles for lower layers 25 Isolation Plate 6,26 Electromagnet 6a, 26a Magnetic pole 6b, 26b Coil 6c, 26c Yoke 7,27 Static magnetic field band 8a, 28a Outer layer solidification start point 8b, 28b Inner layer solidification start point 9a, 29a Outer layer solidification shell 9b, 29b Inner layer Solidified shell 10,30 Roll kiss point 11,31 Multi-layer slab

Claims (2)

[Claims] 1. A basin formed by two rolls and side weirs provided on both sides of the rolls has different lengths.
In a continuous casting method of dipping a book pouring nozzle, pouring different kinds of molten metals respectively by the pouring nozzles to form upper and lower two layers of molten metal layers to produce a clad steel sheet, both sides of the roll A magnetic pole is placed on the surface to form a boundary layer by the static magnetic field band in the pool, and molten metal that forms the outer layer solidified shell above the boundary layer and molten metal that forms the inner layer solidified shell below the boundary layer are injected. Then, the clad steel sheet is manufactured by integrally combining the solidified shells of the inner and outer layers at roll kiss points to produce a clad steel sheet. 2. A basin formed by two rolls and side weirs provided on both sides of the rolls has different lengths.
In a continuous casting method of dipping a book pouring nozzle, pouring different kinds of molten metals by the pouring nozzle to form upper and lower two molten metal layers in a pool, and manufacturing a clad steel plate, A long injecting nozzle for injecting molten metal into the lower layer is provided with a horizontally extending separator plate, and magnetic poles are further arranged on both side surfaces of the roll to form a static magnetic field band at a position overlapping with the separator plate. And molten metal that forms the outer layer solidified shell in the upper layer of the boundary layer due to the static magnetic field band, and molten metal that forms the inner layer solidified shell in the lower layer, respectively, and the solidified shells of the inner and outer layers are integrally combined at the roll kiss point. A method for continuously casting a clad steel sheet by twin rolls, which comprises producing a clad steel sheet by a twin roll.